Method of smelting sulfid ores.



H. L. DOHERTY.

METHOD OF SMELTING-SU'LFID ORES. APPLICATION FILED APR.20.19H- RENEWEDJAN. 19,1915.

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METHOD OF SMELTING SULFID ORES. A PPLICATlONfILED APR. 20. I9!!- RENEWEDMN. 19, 1915. l

l 9 mam Q Patented Aug 1?, 191.5.

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HENRY L. DOHERTY, 0F NEW'YORK, N. Y.

METHOD OF SMELTING SULFID ORLES.

Specification of Letters Patent.

,Patented Aug. 17, 1915.

Application filed April 20, 1911, Serial No. 622,360. Renewed aanuary19, 1915. Serial No.'3,154.

which in their oxidation generate suflicient heat to er'mit of thembeing used as fuels.

The 0 ject of my invention is to cheapen the cost of smelting sulfidoresby utilizing in the smelting operation the surplus heat developed inthe-roasting of the ores,-and the combustion gases given ofi in the reduction of the ore. c

- My invention consists, briefiyIstated, in burning the fairly richsulfids (preferably concentrates) under such conditions that the surplusheat of the oxidation can be utilized to heat the .retorts or otherchambers in which the metal is reduced from the oxidized ore, mixing theoxidized ore with carbon, heating the mixture in the before-mentionedretorts and conducting to a portion of the retort furnace thecombustible gases generated in the retorts during the reduction of themetal and burning the same therein to assist in supplying heat for the Ireduction of the metal.

In the accompanying drawings I have shown diagrammatically an apparatuswhich may be operated to carry out my invention inthe smelting of sulfidores of Zinc,

and have limited my description of my in- ..vention to this applicationof it. It is to be understood, however, that I do not limit my inventionto the smelting of zinc ores but claim it lIl-GOIIHBCtlOIl with all andany one of the several. uses to which it may be applied.

In the drawings, Figural, is a cross-section through a furnace forcarrying out my invention in its preferred form on the line r-B of Fig.2. Fig. 2 is a part front elevation of the front of the same furnaceshowing the arrangement of the burners, gas oif-takes, etc. Fig. 3 is apart cross-see tion of a direct-fired furnace using my in ventionembodyingthe modifications of the gangue of the ore.

apparatus-of Figs. 1 and 2 which is regulred to adapt it to directfiring. Fig. 4: 1s a part cross-section on the line A B of Fig. 2,through the retort-gas burner. Fig.

is a detail of one of the retort-gas conduits. Fig. 6 is a detail of oneof the connecting PIPES from the condensers to the retort-gas'conduits.Fig. 7 is a diagrammatic plan' of the apparatus shown in part in Figs. 1aiid 2.

In the preferred method of carrying out my invention, the crude blendeor sulfid ore is first crushed in crushers, l, and then con: centratedin any suitable form of concentrators, 2. Here the comparati'velyfinesulfid mineral (blende) is separated from the The separated sulfid isnext dried in the driers, 8, (when a Wet method of concentartionhas-been used) and then passed to the grinding mills, 4. Here the sulfidis reduced to powder. The degree of fineness to which it is necessary toreduce the ore varies with various ores, but should always be at least100 mesh. The finely powdered sulfid is next distributed by theconveyors 5 and 5" to the feed chutes, 6, of fuel burners, 7. Theselatter may be of burning of powdered fuelsuch, forinstance, as are incommon use in the firing of .80 almost any type in common use for thethe recuperators 12 through the passages 26. a

The powdered blende in suspension in the air current burns according tothe reaction,

furnaces, 24. forthe coi'nbustion of the Zine sulfid should berestricted to give only a relatively small excess. count of the hightemperature, an objectionably large proportion of the metal willbeoxidized to sulfate, as described-above. When this takes place thesubsequent treatmentof the oxidized ore is complicated owing to thenecessity for leaching out the sulfate and treating it separately(usually by an electrolytic method) from the oxid. As this method ofreduction is not ase'conomical as the direct reduction by smelting I aimto avoid the necessity for the introduction of any subsidiary treatmentby avoiding in the first'place the formation of ZnSO, as far aspossible. Tl'lOlGfOl'G, I prefer to worlrwith' the theoretical 'quantityof or only a slight excess of-air, wlierelrvthe formation of sulfate islargely avoided. Under this condition, a small portion of the blendeusually escapes oxidation.' This separates almost entirely fromtlie'gases in the furnace itself and in the flues of the recuperators,from whence it can be raked out through the openings 17 and 19 providedfor this purpose in the walls of the furnace and recuperators,respectively. Although mixed with ZnO this ZnS may be re-injected intothe furnace with a fresh lot of raw ore and occasion but very littleless in the efficiency of the process. In the furnace, the alreadyfinely powdered ZnS is still further disintegrated by the process ofoxidation, producing very finely divided oxid of the metal which isreadily flotant in the rapidly moving current of, gaseous SO, and N Thehot combustion gases bearing the oxid separator may be the customary baghouse with bags of asbestos fabric, or any other form that is suited tothe operation required. Such method of treatment, however, I do notclaim herein. v

The ZnO reco ered in, the separator is mixed with the proper proportionof carbon (in. the form of anthracite 'coal or coke), the proportionofcarbon being from 50 to of the weight of the ZnO. This rela tivelylarge excess is provided to prevent the formation of CO in theretortswith the resulting large deposition of zinc oxid in the condensers. Themixture of ZnO and Otherwise, on accarbon is charged into the retorts,1-8, and the condensers, '15, put in placefandfluted. The sheet metalconnections, 16, connecting each of the retorts 18 with its coiiperatinggas pipe, 20, are next put in place and the gate valve or dampers, 21,on the short connections 22 attached to the pipes 20 at ap- 'tained at aten'iperature of between"8=$0" and 1000 F. This being below the boilingpoint'of zinc the vapor condenses onthje walls of the condensers 15 andthe liquid Zn collects in the bottoms of the condensers.

The CO (accompanied by small 'propoftions of H N and usually tracesofGO'ig) passes out of the condensers 1'5, througlr tlie connections 16,gas conduits 20, 13 and eo inections 34, to the gas ports 25 of ap'ortie'n H of the retort furnace 23,"-preferably separate from the mainportion 24, which is fired by sulfid ore, the quantity of CO pro duoedin the retorts not being suflicient' to fire the entire furnace. It'isof course' 'atlvantageous to fire with the "CO from the retorts to theextent to which that is-a vai able should the sulfid be insufficient forth e purpose. Air for the combustion of'f tli e C(Tenters through thedampered airfi 'ssages 27. The combustion gases, sweeping-around theretorts 18, pass toth'e recuperators 12, separate from cherat.

perators 12, and thence to the stack. Should the natural draft of thefurnace not be-sufficient, it may be supplemented by adiri itting airunder pressure to the passage- 10 from a connection 8' from the air mainThe discharge of this air through. the 1 ssage 10 induces a flow of COfrom the mhn 13 and more'air from the 'recuperator, the one hand, andexerts a forcing ac'ti-pn on the furnace draft, on the other. The retortfurnaces for zinc smelting often constructed so that the furnace Cliaiu-1 her is continuous from end to end ioffthe block, with separate burnersor firepladds atintervals along each face of. the furnace. Sometimes,however, (and this is the". i1 struction best adapted for carrying outprocess) themain furnace chamber is vided into sections by walls thrownac half-way between fire-places. It is notifie essary, however, to adoptthis construction, in the main, to adapt a furnace to carry 130 out my.invention, but is always advisable Sincethe theoretical flametemperature of v the reaction with cold air is nearly 3400" F., thereisno practical difliculty in securing a sufli'cie'nt temperature in theretorts as long as. the number of retorts to be heated by the roastingflame is properly proportioned to the heat available. By preheating theair used for the combustiomin the manner hereindescribed, by the heat ofthe efliuent com 'bustion products of the furnace, the heat availablefor heating the retorts is still further increased.

The modification of my invention, for the carrying mat of which amodified form of apparatus is shown in Fig. 3, diifers from theforegoing simply in that the metallic oxid is burned in fragments on thegrates 28 of furnaces 29in a manner similar 'to coal. A blast of airtosupport the combustion enters the ashpits 30 from the air I pipes 36connected with the air main 37.

In this form of my invention the ZnO passes in small-part into the gasesin the form ofdust, but the bulk of it works .throughthe grates 28 intothe ash pits '30 of the furnaces 32 and is removed therefrom similarlyto the ash in ordinary coal firing The combustion gases, as before,sweep around the retorts, thence pass through the with special referenceto the treatment of zinc sulfid, it is to be understood that I do.

recuperators' and' ZnO separators to the stack.

While. my invention has been described not limit myself to its useiwiththis mate-' rial alone. It may be applied, more or less modified to su tthe peculiar demands in each case, to the treatment of iron sulfidsorany similar mineral whose oxidation de velops a surplus of heat. Forexample, coal for coke may be mixed with the sulfid, when when thesulfid is necessary, particularly to be burned-on grates.

T he" expression. fresh sulfid as used in the claims is intended todesignate untreated sulfid, and is of'course not intended to implyfreshly mined sulfid orany similar meaning. Having described myinvention, what I claim is:-- I

1. The process of treating zinc sulfid which comprises pulverizi'ng thesulfid,

burning the pulverized sulfid. in aerial susproportion of carbonaceousmaterial and smelting the said'm'ixture by the heat generated by thecombustion of fresh sulfid.

2-. The process of smelting sulfid orewhich comprises burning the saidore with sufiicient air to insure the oxidation of the same, mixing theoxidized ore with a reducing material, and subjecting the'mixture ofoxidized ore an d reducing material to the heat developed by theoxidation of fresh 3. The process of smelting sulfid ore which comprisesburning the said ore With sufiicient air to insure oxidation of thesame, mixing the oxidized ore with a reducing material and subjectingthe mixture of oxidized ore and reducing materialto heating by heat,developed by the oxidation of fresh sulfid ore and by the combustion ofthe combustible gasesgiven off during. the heating of the said mixtureof oxidized ore and reducing material.

4. The process of smelting zinc sulfid ore which comprises burning thesaid ore with air, mixing the zinc oxid resulting from the oxidation ofthe said ore with carbonaceous material, and subjecting the mixture ofzinc oxi and carbonaceous material to-the heatdeveloped by the oxidationof fresh zinc sulfid.

5. The process: of smeltingzinc sulfid ore which comprises burning thesaid ore with air to form zinc oxid, mixing the zinc oxid resultingfromthe'oxidation of the ore with carbonaceous. material, and subjectingthe mixture of zinc oxid and carbonaceous material to. heating by .heatdeveloped by the burning of fresh sulfid and by the combustallic :baseof the said ore is converted into oxid, mixing the metallic oxid. with.carbonaceous material and subjecting the re- 'ulting mixture to the heatdeveloped by the oxidation of fresh sulfid ore. a

; 7. The process of smelting sulfid" ore which comprises burning thesaid ore with air, whereby the major portion of the Ine-v tallic baseofthe said ore-is converted into oxid, mixing the metallic oxid with.carbonaceous material and subjecting the mixture to heating by heatdeveloped by the oxidation of freshisulfid ore and by the combustion ofthe combustible gases given off.

during "the heating of the said mixture of metallic oxid andcarbonaceous material.-

8. The process-of smelting sulfid ore which comprises, pulverizingthe-said ore, suspend-- ingl-the. pulverized ore in a current of-air, lm x h cient additional" preheated air to insure the presence in theadreft-current offsuflicient I the ore-laden air current sulfioxygen for theoxidation of the ore, subject- "ing the mixture'of pulverized ore andairlto fa temperature sufficient to ignite the same, transferring aportion of theheat in the I products from the combustion-of the said fsulfid ore to afresh portion of air,separating from the said products ofcombustion the suspended metallic oxid therein, mixing the said oxidwith carbonaceous material 1n quantity sufficient to reduce the saidoxid, and heating the resulting mixture by heat 5' developed in theoxidation of fresh sulfid ore.

9. The process of smelting sulfid ore "which comprises pulverizing thesaid ore,

' suspending. the pulverized ore in a current of air, mixing with theore-laden air current sufiicient additional preheated air to insure thepresence in the draft current of sufficient oxygen for the oxidation ofthe ore,

" subjecting the mixture of pulverized ore and a air to a temperaturesufficient to ignite the v same, transferring a portion of the heat inthe products ofthe combustion of the ore f to a fresh portion of air,separating from J the products of combustion the suspended metallic oxidtherein, mixing the said metallic oxid with carbonaceous-material inquantity sufiicient to'reduce the said oxid,

. heating the resulting mixture by the heat K developed by the oxidationof fresh suliid ore, whereby the said oxid and the said car-" bonaceousmaterial react to form the free metal. and carbon monoxidmnd burning thesaid carbon m'onoxid to heat a portion of the said mixture of metallic.oxid and carbonaceous material.

' 10. The process of smelting zinc blende ore wh1ch-comprises pulverizng the said blende, suspending the pulverized blende in j a current-ofair; mixing the ore-laden air it current with sufficient additionalpreheated air to insure the presence in the dra current of enough oxygenfor the oxidation of "the blende, subjecting the mixture of pulverizedblende andair to a temperature suf- I ficient to ignite the same,transferring a portion of the heat in the products of the combustion ofthe said blende to a fresh portion of air, separating from the saidprod: -ucts of combustion the zinc oxid formed by the combustion of theblende, mixing. the

said oxid with carbonaceous material, ,in quantlty suflicient to reducethesaid oxid and heating the resulting mixture by heat developed in thecombustion of a fresh'portion of blende, whereby the zinc in said oxidis reduced to the metallic state.

11. The process of smelting zinc blende ore which comprises pulverizingthe said blende, suspending the pulverized blende in a current of air,mixing the ore-laden air current with suificient preheated air to insure the presence in the draft current of enough oxygen for theoxidation of the blende, subjecting the mixture of pulverized blende andair to a temperature suflicient to ignite the same, transferring aportionof the heat in the products of the'combustion f of the blende toa fresh portion of air,' separating from the said products of combustionthe zinc oxid formed bythe combustion of the blende, mixing the saidoxid with carbonaceous material in quantity sufficient to reduce thesaid oxid, heating the resulting mixture by heat developed'in thecombustion of a further portion of blende, whereby the said oxid and thesaid carbonaceous material are caused to react to form metallic zinc andcarbon monoxid and burning the said carbon monoxid to heat a portion ofthe said mixture of zinc oxid and carbonaceous material.

Signed at New York city in the county of New York and State of New Yorkthis 19th 85 day of April A. D. 1911.

- HENRY DOHERTY.

Witnesses:

FRANK L. BLACKBURN, Tnos. I. CARTER.

